1. Field
The present subject matter is related to an image processing apparatus configured to perform image processing for recording text and images and an image processing method thereof.
2. Description of Related Art
Recording text at high resolution is desirable for applications such as business documents, as text quality in recorded images is of significant importance. However, when processing high resolution color images, the amount of image data transferred to a printer increases, which also causes the processing load at the printer for storing and processing this data to increase.
Sometimes, methods are used to transfer multi-value image data from a printer driver to a printer, the printer then generates record data by reducing the gradation level of the multi-value image data, and then form images to a recording media on the basis of the record data having a reduced gradation level. This method has such advantages as being able to distribute the processing on the printer driver side over multiple printers.
PCT Japanese Patent Translation Publication No. 2003-508827 discloses a method in which data corresponding to a black text image unit and data corresponding to a color image unit is divided from input image data, each type of data is compressed and transferred to a printer, and then the printer composites these two types of data.
However, new problems are created when multi-value color image data and multi-value text data transferred to a printer is quantized and then composited according to the technique disclosed in PCT Japanese Translation Patent Publication No. 2003-508827. Specifically, ink dots regarding boundaries of the color image and text overlap, which causes a problem of degrading text quality. This occurs in such cases as when quantization processing is performed on each type of data as a type of error diffusion processing resulting in quantization errors propagating to peripheral pixels, or when the resolution of transferred image data and text is different. This is due to the generation of data representing ejections of ink on pixels which originally had concentration values of zero caused by propagation of quantization errors to peripheral pixels or conversions of resolution. When recording images on a printer on the basis of such text data and image data, images with low text quality are recorded.